DocomintUnit Converter
Convert length, weight, temperature, volume, area, and speed between metric and imperial units.
What is a Unit Converter?
Covers the conversions that come up most when reading a recipe in the wrong measurement system, checking a product spec sheet from another country, or converting a road sign's speed limit — six categories (length, weight, temperature, volume, area, speed) rather than a single-purpose converter, so you don't need six different bookmarked tools.
How to use the Unit Converter
- Pick a measurement category — length, weight, temperature, volume, area, or speed
- Choose the units to convert from and to, and enter a value
- The converted value appears instantly, calculated on your device
Formula
Target value = Source value × conversion factor(from → to), except Temperature which uses a formula with an offset
Length, weight, volume, area, and speed are pure multiplicative scales. Temperature has different zero points across scales (0°C isn't 0°F), so it converts with a formula rather than a single multiplier.
Example
A European oven recipe calling for 180°C converts to 356°F in Temperature mode — useful before setting a Fahrenheit oven dial, since temperature conversion doesn't scale linearly like the other categories (0°C isn't 0°F).
Common mistakes
- Assuming temperature converts the same multiplicative way as the other five categories — it needs an offset calculation, not just a multiply.
- Not realizing this uses US volume units (gallons, quarts, pints, cups) — UK imperial volume units are sized differently and aren't the same numbers.
- Converting an area or volume value using the linear length factor directly — area scales by the factor squared, volume by the factor cubed.
- Switching categories (e.g. from Length to Weight) without noticing the From/To unit dropdowns reset to that category's defaults.
Frequently asked questions
How accurate are the conversion factors?
They use the standard internationally defined conversion constants (e.g. exactly 1609.344 meters per mile, 0.45359237 kg per pound) — the same figures NIST and other standards bodies publish, not rounded approximations.
Why is temperature conversion different from the other categories?
Length, weight, and the other categories are pure multiplicative scales — double the value in one unit and you double it in the other. Temperature scales have different zero points (0°C isn't 0°F), so converting needs an offset, not just a multiplication factor.
Are the volume units US or imperial (UK)?
US customary units — a US gallon, quart, pint, and cup are all sized differently from their UK imperial counterparts, so don't mix figures from a UK recipe with this tool's volume conversions.
Why can't I convert length to weight, or mix categories?
Length and weight measure fundamentally different physical quantities with no fixed conversion factor between them — you can only convert within one category (e.g. length to length) at a time.
Is my numbers uploaded anywhere?
No — Unit Converter runs entirely in your browser using JavaScript/WebAssembly. Your numbers is never sent to a server.